Ditch the Carb, Not the Fat

Its that time of year again when many of us are planning to start a healthier lifestyle. The incorrect advice to follow a low-fat diet persists so its worth reminding ourselves of some of the key reasons why we should aim to reduce carbohydrates and sugars instead of fat.

Low-Fat Diets Paradoxically Increase Blood Fat levels.

Fats in the bloodstream are known as triglycerides. A higher level of triglycerides in the blood can increase the risk for heart disease. High levels of triglycerides are also a very common feature of diabetes and diabetics are up to five times more likely to have heart disease than non-diabetic people.

For decades, the idea has perpetuated that eating fat will cause the level of triglycerides in the blood to increase. However, when we look at the data from scientific studies it is clear that this is not the case. In fact, every dietary trial that has been done has found that a low-fat diet causes the level of triglycerides to increase - no studies have found that increased dietary fat increases triglycerides.

Initially, this may seem to be a paradox, however, what these and other studies reveal is that dietary fat is not the villain it was once thought to be. A low-fat diet will inherently involve the consumption of more carbohydrate and sugar. Guidelines from health authorities actively encourage people to substitute foods that contain fat with foods that are carbohydrate based. What is often overlooked is the effect that a low-fat / high-carbohydrate diet has on blood glucose levels.

The chart below compares the effects that a high-carbohydrate diet has on blood glucose levels with the effects of a high-protein / higher fat content diet, during a 24 hour period. It can be seen that the high carbohydrate diet causes wild fluctuations in blood glucose and much higher levels of blood glucose overall. It is worth pointing out that the carbohydrate content of the high-carbohydrate diet used for this analysis was 55 percent - which is considerably lower in carbohydrate content than the diet many people are consuming today.

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Why is this so important? Well, high blood glucose is a serious situation that the body has to rectify as a priority. High levels of blood glucose cause circulatory problems and damage to the inside wall of blood vessels. And a high level of blood glucose triggers the release of the hormone insulin, which is required to lower blood glucose levels.

Insulin enables the body’s cells to use some of the glucose, but if there is too much glucose insulin converts the excess glucose into fat (triglycerides). This explains why low-fat /high-carbohydrate diets increase blood triglyceride levels.

It is worth mentioning that the presence of a high level of insulin, in response to the high glucose level, by definition, blocks the ability to burn body fat. Insulin is a fat storing hormone. This is one reason my people who follow a low-carbohydrate diet tend to lose more body fat.
When the level of triglycerides is high we also find a low level of HDLs - the so called ‘good cholesterol’.  Again, every single dietary trial completed has found that a low-fat / high-carbohydrate diet reduces HDL levels.

We can really start to appreciate the topsy turvy world we live in where HDLs are called ‘good’ and at the same time low-fat diets are promoted as healthy - the very diet that is the best way to reduce HDL ‘good cholesterol’ levels.  Just one of the many fundamental inconsistencies associated with the lipid hypothesis.



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